Thiamine (B1)

Thiamine, also called vitamin B1, is a water-soluble vitamin found in virtually every cell in the body. Water-soluble vitamins are stored in the body in limited amounts. They leave the body through the urine. For this reason, it is a good idea to have them in your daily diet. Thiamine is also available as a supplement and by prescription as an injection.

Function

Thiamine helps to process carbohydrates, fats, and proteins. It is needed to make adenosine triphosphate (ATP), which is the body’s main energy-carrying molecule. Thiamin is also necessary for memory and other brain functions.

Recommended Intake

Age Group
Recommended Daily Allowance (RDA)

FemalesMales

0-6 months0.2 Adequate Intake (AI)0.2 (AI)

7-12 months0.3 (AI)0.3 (AI)

1-3 years0.50.5

4-8 years0.60.6

9-13 years0.90.9

14-18 years1.01.2

19 and older1.11.2

Pregnancy and Lactation1.4n/a

Thiamin Toxicity

There have been no adverse effects reported with taking too much dietary thiamine. The body excretes any excess amount that is consumed. In rare instances,
coughing,
hives, itching, swelling, and breathing difficulties have occurred from thiamine injections given by doctors.

Major Food Sources

Thiamine is mostly found in whole-grain and enriched grain products like bread, pasta, rice, and fortified cereals. These foods are enriched with thiamine because the vitamin is often lost during the refining process. Pork, liver, and other organ meats are naturally high in thiamine. This table lists good food sources of thiamine.

FoodServing Size
Thiamin Content
(mg)

Lentils, cooked½ cup0.17

Green peas, cooked½ cup0.21

Pork, lean3 oz0.81

Fortified breakfast cereal, wheat, puffed1 cup0.31

Wheat germ breakfast cereal, toasted, plain1 cup1.88

White bread, enriched1 slice0.23

Whole-wheat bread1 slice0.10

Pecans1 ounce0.19

Spinach½ cup0.09

Cantaloupe½ fruit0.11

Milk1 cup0.10

Egg, cooked, hard-boiled1 large0.03

Orange1 fruit0.11

Brown rice, long grain, cooked1 cup0.19

White rice, enriched, cooked1 cup0.26

White rice, unenriched, cooked1 cup0.04

Health Implications

Beriberi

Thiamine deficiencies are rare in the United States because thiamine is added to refined grains. However, deficiencies do sometimes occur.
A severe thiamine deficiency can cause the disease beriberi. Beriberi can damage the heart and the nervous system.

Beriberi is still seen in people with alcohol use disorder (AUD), in people whose ability to absorb thiamine is impaired, some people with kidney failure that eliminate thiamine, and in developing countries where foods are not fortified. Treating beriberi with vitamin B1 cures most cases, though severe deficiency can cause irreversible damage.

Wernicke Encephalopathy

A deficiency of thiamine can cause Wernicke encephalopathy (WE), which affects mental status and vision. It is also more commonly seen in people with AUD. WE is treated with thiamane.

Korsakoff Syndrome

WE can develop into Korsakoff’s syndrome. Symptoms of Korsakoff’s syndrome include memory problems, confusion, and emotional changes. Other causes may include brain damage, such as with
tumors,
head injury, or
stroke. If AUD is the cause, avoiding alcohol is an effective treatment. Treatment with thiamine may also be used.

Heart Failure

In people with
heart failure, the heart's ability to pump weakens, and fluid begins to build up in the lungs and legs. Loop diuretics are often prescribed to treat heart failure. However, these drugs can deplete the body of thiamine. Since thiamine is required for normal heart function, this can cause problems. Thiamine supplements may be prescribed in these cases.

Conditions That May Increase the Need for Thiamine

While thiamine deficiency in a healthy person is uncommon, there are conditions that can increase the need for thiamine, making a deficiency possible. If you have any of the following conditions, talk with your doctor about your thiamine needs:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.